Physician Ferguson (Medical Self-Care, etc.) gears this thorough book toward the ""health-concerned'' smoker, a target category that some nonsmokers will find oxymoronic. Ferguson doesn't lecture on the evils of the habit but offers impartial advice on ways smokers can reduce the risk of illness or death. His approach is evenhanded: he cites studies proving that regular exercise decreases death rates and others that repudiate those results but demonstrate that aerobic activity enables smokers to cut down or quit with greater facility. And ``even though the evidence that selenium may help prevent cancer is very encouraging, smokers should not think of selenium supplements as a magic anti-cancer pill.'' The book is replete with intelligent, specific strategies to wean smokers from cigarettesemploying fruits and vegetables, placebos, stress-reduction ideas, peer support, a visit to a cancer ward, etc.and offers the controversial alternative of ``controlled smoking,'' which includes reducing the number of cigarettes smoked and the portion of each cigarette smoked, and switching to a lower-nicotine brand. First serial to Self, Prevention and Medical Self-Care magazines; Prentice Hall Book Clubs alternate; author tour. (July 1)